Streamlining: Student Success Criteria I can describe factors affecting laminar flow, and explain how the design of an item or organism responds to these factors.

Streamlining SPH4C

Drag The frictional forces that act on an object’s motion through a fluid are called drag.

Streamlining To reduce drag, a technique called streamlining is used. Streamlining is the process of reducing turbulence by altering the design (shape and surface features) of an object that moves rapidly relative to a fluid.

Streamlining Streamlined flow is the same as laminar flow. The turbulent wake behind the non-streamlined object is a low pressure region, pulling the object backwards.

Streamlining in Nature Streamlining is found in nature in animals that move quickly though water or the air. Scientists study this streamlining and try to model it in technology.

Testing Models are tested in computer simulations and in wind tunnel and water tank tests. A scale model in a wind tunnel

Drag Coefficients Scientists communicate the amount of drag something has with a number referred to as the drag coefficient (Cd). The lower the drag coefficient the less drag there is.

Drag Coefficients E.g.: A highly streamlined airplane wing is around Cd = 0.050 while an open parachute designed for maximum drag is around Cd = 1.35.

Drag Coefficients In the 1930’s, when gas was inexpensive, most cars had a drag coefficient of Cd = 0.70; today most cars have a coefficient of about Cd = 0.40 and some have coefficients as low as 0.15.

Shapes and Drag Which shapes have the highest drag coefficients? Which shapes have the lowest?

Fluid Dynamics Assignment Describe the types of features used on a particular vehicle (e.g. a sport bike, a locomotive, or a bobsled) to reduce drag.

Examples E.g.: Air dams, tapered light covers and hood, concealed windshield wipers, low profile windshield, flush pillars, flush door handles, flush wheel openings, aerodynamic mirrors. . .